This invention relates generally to vehicle height control apparatus, and, more particularly, to such apparatus which is capable of appropriate control of vehicle height in accordance with a dynamic model of a system relating to the height of a vehicle.
Various types of vehicle height control apparatus have been devised and manufactured where the vehicle height control apparatus is developed so that a vehicle always keeps a normal attitude with a given height by correcting the variation of the vehicle height due to changes in the number of passengers or the amount of load, or the stability of the vehicle by which running is improved by changing the vehicle height in accordance with the travelling state of the vehicle or the state of the road surface.
In such conventional vehicle height control apparatus, vehicle height is controlled on the basis of so called classic feedback control theory with which vehicle height is controlled in connection with each of the respective wheels by driving the vehicle height adjusting members so that the vehicle height detected by the various vehicle height sensors, which are provided for the respective wheels, equals the therefor target vehicle height.
However, since respective vehicle height adjusting members are independently controlled in the conventional vehicle height control apparatus, there has been a problem that vehicle height control at an arbitrary position cannot be effected, since the independent adjustment of one vehicle height adjusting member effects the others. Furthermore, there has been a problem in connection with response time such that it takes a relatively long period of time until a vehicle body assumes a stable attitude after control is started since vehicle height control is performed without considering the mutual interference between the respective vehicle height adjusting members, such that driving of one vehicle height adjusting member affects the other vehicle height adjusting members.